A combustion chamber is disclosed for a gas turbine with a thermal protective lining, as is a seal for the semi-static region between elements of the thermal protective lining. Combustion chambers of this type can be used in large gas turbines, such as stationary, industrial gas turbines.
The combustion chambers for gas turbines are typically lined with thermal protective elements which protect the combustion chamber casing from hot gas of the combustion chamber, and for this purpose, are fastened on supports in the combustion chamber casing, in the form of segments arranged in series along the circumference of the combustion chamber. The protective lining is cooled by cooling air which flows between the supports and the segments. The cooling air can be guided in the direction of the combustion chamber axis, and subsequently added to the fuel in the region of the combustion chamber inlet. Seals are installed at the combustion chamber inlet of the combustion chamber, between the thermal protective elements and the combustion chamber casing. They can prevent cooling air from reaching the combustion chamber between protective elements and casing and influencing the combustion process.
The thermal protective elements can be subjected to movements of varied magnitude and varied frequency.
Movements of lower frequency due to thermal expansions, which are also known as so-called “low cycle fatigue movements”, can occur in the axial direction and also in the radial direction. They can be especially significant in large, stationary industrial gas turbines, since there the thermal expansions, on account of the large dimensions of the component parts, are in a large ratio to the precision with which the gas turbine and combustion chamber are manufactured. The thermally conditioned relative movements mean a challenge in the seal between the thermal protective elements and also in the region around the protective elements. Movements of higher frequency of the thermal protective elements can result from vibrations which can occur during general combustion chamber operation. The operation can induce vibrations of varied frequencies in the protective elements, which due to the natural frequencies of the protective elements can lead to increased vibrations of protective elements and supports. They are also known as so-called “high cycle fatigue movements”, and are of smaller magnitude and of higher frequency in comparison to the thermally induced movements. They can especially reduce the reliable operating period of the protective elements.
The thermal protective elements, their supports, and also adjacent component parts are basically static. Since the interspaces between individual protective elements and also the spaces between the protective elements and adjacent component parts, however, are subjected to the aforementioned relatively large movements, the protective elements and the seals for the interspaces can be considered to be in a semi-static range.
There are various measures which are known for damping of vibrations in a combustion chamber. For example, the magnitudes of vibrations can be reduced by the amplitudes and frequencies of the vibrations being damped or interrupted. This, for example, can be realized by conscious control of the combustion process, or by acoustic damping elements in the combustion chamber which dissipate the energy of the oscillations.
EP 990 851 discloses a method for acoustic damping of vibrations inside combustion chambers by Helmholzt damping. There, a combination of Helmholtz resonators with a further damping medium, such as a plurality of plates with openings for a cooling flow, is disclosed.
U.S. Pat. No. 6,357,752 discloses the use of brush seals in the region between the end, in the flow direction, of a combustion chamber for a gas turbine and the first stator row of the gas turbine. It involves there a brush seal of double construction, wherein the pressure drops across the first seal and second seal in opposite directions. The disclosures of EP 990,851 and U.S. Pat. No. 6,357,752 are hereby incorporated by reference in their entireties.